Pulled into Stubb Stewart State Park in NW OR and hooked up. Monitor read 50 amps and everything worked. Got up the next morning and turned on the coffeepot. A few minutes later pushed down the toaster and everything died. Batteries were down to 11.8V. System shutdown, b ut AC's both still worked. Checked all the fuses, inverter fuses, etc. Started the gen and everything worked including the batt charger. Finally scratched my head and called Monaco LLC. Tech told me to check that the post was hot on both sides (even tho the system monitor still read 50A). Asked the local ranger to check the post... and they found that one side was dead. Now it

That's why it's important to know exactly what's in the pedestal box BEFORE you plug in. There's an easy to make tester, see link below, with parts readily available from your local Home Depot. I made one in about 45 minutes....check it out...Dennis

The only problem with a multimeter reading on a park post is that it just tells you if there is any voltage present at all. It does not tell you if the pole outlet has the capacity to furnish the amperage that you may need. In other words, if a single strand of a wire makes contact in a loose connection, you will read the correct voltage but that single strand cannot supply 50 amps of current.
We all are familiar with the problems we can have in our coach if a battery connection is loose or corroded. The same thing can happen at a RV park pole. This is where a good EMS is necessary. This will not only confirm the presence of voltage and the correct polarity, but it will also alert you if one leg cannot supply the voltage/amperage needed for proper operation.

As for the home made tester, Nice device but I need one that monitors INLINE.

If I can talk my wife into cutting out a day early I'll get the parts but my plan is this.

I have an autoformer, installed, I will replace the box on the outlet part of the install kit with a slightly larger one and install two fused transformers (Very small fuse) 12 volt No reason do do this save for I'd rather play with 12 volt. One will be X-W one Y-W. These will run to a pair of AC-Voltmeters. I may also meter some other stuff just for fun. Include a NEON indicator from W to G as well (posibly from X and Y to G as well) Combining all functions in one indicator box.

These will measure IN USE voltages. PRE autoformer no less.

Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377